Abstract

Channel change induced by tributary sediment injection to a regulated, gravel-bed river is described for the River Rheidol, U.K., eighteen years after dam closure. Morphological and sedimentological data are presented for an aggrading reach. A primary lobate bar appears to have initiated flow separation and the subsequent construction of channel-side berms. Hydraulic sorting has operated to produce both longitudinal and lateral particle-size reduction, and selective particle-size dispersal appears to be an important process influencing channel change. The channel is adjusting to a lower width-depth ratio form, of smaller capacity, and with a steeper slope.